Shown in FIG. 1 is a simplified communications network scenario that includes both a Signaling System 7 (SS7) and a Transmission Control Protocol/Internet Protocol (TCP/IP) communications network, generally indicated by the numeral 100. Network 100 includes both a conventional voice type calling party 102 and a computer terminal based data type calling party 104. Both calling parties are communicatively coupled to an originating End Office (EO) or Service Switching Point (SSP) 106. With particular regard to signaling type communications, SSP 106 is generally connected via an SS7 network 108 to an SS7 signaling message routing node, Signal Transfer Point (STP) 110. Coupled to STP 110 is an SS7 message accounting and billing system 114 which is used to track SS7 signaling query messages that are destined for an SS7 database node, Service Control Point (SCP) 112. SCP node 112 might include an 800 number database, a Line Information Database (LIDB), Local Number Portability database (LNP), or other database services typically associated with the Public Switched Telephone Network (PSTN).
With particular regard to SS7 communication networks and the protocol stack typically employed therein, it will be appreciated that the overall stack can essentially be divided into two segments or layers: a lower level Message Transfer Part (MTP) layer and a higher level signaling application layer. In fact, the MTP layer, as described above, is comprised of three sub-levels that are identified as layers MTP1, MTP2 and MTP3. These three layers generally correspond to the physical, data link, and network levels as defined in the International Standards Organization (ISO) Open System Integration (OSI) protocol standard, and each layer can be configured to operate under one of many layer-specific protocols depending upon the particular network configuration scenario. For instance, the MTP1 layer protocol could be configured as DS0A, V.35, etc. Signaling application layer protocols commonly employed in an SS7 network include Transaction Capabilities Application Part (TCAP)/Signaling Connection Control Part (SCCP), ISDN User Part (ISUP), Telephone User Part (TUP), Mobile Application Part (MAP) and Broadband ISDN User Part (BISUP). With respect to the OSI model mentioned above, these SS7 signaling application protocols essentially correspond to OSI layers 4 through 7, and in some cases a portion of the OSI layer 3. Such signaling application layer protocols are concerned primarily with facilitating call setup/teardown and various call related services (e.g., toll free service, local number portability, calling name delivery, etc.). In general, it will be appreciated that the lower level MTP layers are concerned with, and responsible for, ensuring reliable transport of a signaling message between applications residing on different SS7 network nodes.
In light of the previous discussion, it will be appreciated that within an SS7 signaling network, SS7 signaling protocol messages are typically transmitted over dedicated communication links that employ an MTP transport protocol suite.
Returning to FIG. 1, it will be noted that further connected to SSP 106 is an Internet Service Provider (ISP) 116, which is also communicatively coupled to an Internet Protocol communications network 118, such as the Internet. As such, ISP 116 effectively provides a calling party that is served by SSP 106 with access to the Internet 118. Connected to and generally contained within the Internet “cloud” 118 are a large number of data packet routers, one of which is shown in FIG. 1 as router 120. Further coupled to Internet data router 120 is a database node 122 and a billing system 124. Database node 122 might include domain name information, presence or status information, or any number of database applications utilized by Internet type service providers or e-commerce type operators. In a manner similar to that described above, billing system 124 is coupled to router 120 so as to generally track messages destined for Internet database node 122.
With particular regard to IP-based communication networks and the protocol stack typically employed therein, in a manner analogous to that described above for SS7/MTP protocols, it will again be appreciated that the overall stack can essentially be divided into two components: a lower level or suite of transport related protocols and a higher level signaling application related layer. For the case of a Transmission Control Protocol (TCP)/IP based communication network, it will be appreciated that the transport protocol suite, as referred to herein, refers to OSI layers 1 through 3. Consequently, with regard to TCP/IP based communication, OSI layers 4 through 7 are referred to herein as the higher level or signaling application related layers. Again, as both the ISO OSI and the SS7/MTP protocol models are well known to those skilled in the art of packet network communications, a detailed description and discussion of the basic OSI and SS7/MTP models is not presented herein. A detailed discussion of the OSI model can be found in Communications for Cooperating Systems OSI, SNA, and TCP/IP by R. J. Cypser, Addison-Wesley Publishing Company, Inc., 1991. Similarly, a detailed discussion of the SS7/MTP protocol can be found in Signaling System #7 by Travis Russell, 2nd ed. McGraw-Hill, Inc., 1998.
Given the configuration of network 100, and the inherent incompatibility of the two communication transport protocol suites (MTP vs. TCP/IP), there is no way that an Internet protocol node can directly or indirectly access a database node in the SS7 component of the network. Similarly, there is no mechanism whereby an SS7 node can access a database node in the IP component of the network.
One solution to the above stated problem is to employ a stand-alone protocol converter node 126 that resides in front of the SS7 SCP node 112 as indicated in FIG. 2. Protocol converter node 126 is capable of receiving a TCP/IP based non-SS7 database query message (i.e., a message that employs a non-SS7 signaling application protocol such as session initiation protocol (SIP), H.323, etc.) and translating this message into an SS7/MTP formatted query message that can be processed by SCP 112. However, as indicated in FIG. 2, such a configuration makes the problem of message accounting/billing considerably more complicated, as all query messages destined for SCP 112 do not necessarily pass through STP 110. Furthermore, such a configuration requires that a network operator install and maintain separate protocol converting nodes, which generally increases network complexity and creates additional OA&M burdens.
What is needed is a system and method of providing a packet routing node that is capable of facilitating communication between networks that employ differing transport level protocols (e.g., MTP vs. TCP/IP) and differing signaling application level protocols (e.g., SS7 vs. SIP). Also needed is the ability for such a multi-protocol routing node to simultaneously provide centralized message accounting and billing capability in a multi-protocol communication network environment.